>>56367833The problem with GF (and nostalgic fans) is not allowing subsequent regions to have their own identity, each region should have its own unique ecosystems and not just copy and paste Machamp, Gengar, Snorlax, Charizard, and Pikachu across all regions.
You want to give a reference or fanservice, limit it to a cameo, give new Pokemon a chance, if someone wants their old Pokemon for competitive reasons or personal taste, it's fine to give them that as a postgame that doesn't affect the region's lore, even with small details like NPCs mentioning they've never seen that Pokemon, but don't put them in the middle of the adventure. It makes no sense for you to sell me Lucario as a super rare and exclusive Pokemon from Sinnoh, if in Unova you can find Riolu as if it were a stray dog.
You want a character to have a certain Pokemon, that's fine but justify it, whether it's a foreign trainer, it's an exotic pet, or it was given as a gift between regions like pandas in real life.
